Construct a proof to show that the following claims are true. these proofs only require use of the rules for, conditional, biconditional, conjunction and disjunction.
c) A → (B → C) ⊢ (A ˄ B) → C
d) P ↔ Q ⊢ Q ↔ P
e) (A v B) → C, (C v B) → A ⊢ A ↔ C